<!DOCTYPE html>
<html>
<head>
    <meta charset="UTF-8">
    <title>Document</title>
    <style>
        
    </style>
</head>
<body>
    
</body>
<script>

    function fn(){
        let a = 10;
        let b = 20;
        let c = 30;
        return {
            get a(){
                return a;
            },
            set a(v){
                a = v;
            },
            // ...
        }
    }

    const o = fn()
    // console.log(o.getA())
    console.log(o.a);
    // o.setA("hello");
    o.a = "hello";
    console.log(o.a)

    
</script>
</html>